What is different from each other sperm?


25/07/2012

The scientists compared the genomes of normal cells and sperm. Researchers from Stanford University told the journal Cell, they opened after reading the DNA of human sperm.

Not even an expert in scientific matters will note that the human genome was sequenced nearly a decade ago. To understand why the sperm genome deign article in Cell, remember that man, as everyone knows, has 23 pairs of chromosomes. However, the sex chromosomes of all cells without a pair, that is, the egg and sperm have just 23 chromosomes.

Daughter cells receive from sexual homologous chromosomes (which have the same genes, but different alleles). For example, both chromosomes contain the gene eye color, but one of them will contain an allele hazel color and the other - green. In this case, homologous chromosomes undergo recombination - they exchange pieces of DNA. During chromosome recombination diverge eggs and sperm and then randomly joined in the fertilized egg, thereby achieving a great variety thus obtaining genome and therefore increases the chances of survival of species.

All this suggests that the spermatozoa in their genome to be very different from the other cells of the body, but so far no one has not got around to comparing these genomes. Stanford researchers conducted an experiment with 40-year-old man having healthy children and healthy sperm. Researchers have sequenced the genomes of 91 sperm. The sequences obtained were compared with the DNA experts conventional experimental cells.

It was found that the sperm genome is surprisingly diverse. According to the researchers, the average sperm DNA recombination was carried out 23 times. Some spermatozoa this value is much higher. Since mutations fared similarly. For example, when two sperm maturation in general have lost a chromosome. On average 25-36 replaced by single nucleotides per cell. Some mutations have been favorable, and some, on the contrary, could lead to the death of the embryo in the case of a compound of the sperm to the egg.

However, no abnormalities were observed in children, and the sperm of the test seemed perfectly healthy. This suggests that even if a person has a family tree is healthy, his children may have genetic abnormalities.

According to the materials Sciencemagis.ru


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